The JPL 2022d X/Ka Celestial Reference Frame

The X/Ka-band (8.4/32 GHz) Celestial Reference Frame became one component of the ICRF-3 in 2018. In the four years since, the X/Ka data set has increased by about 60% as well as adding the much needed north-south geometry from Japan to Australia. The latest solutions show that formerly large spherical harmonics distortions are greatly reduced with the Z-dipole term reduced from 314 μas to statistical insignificance and with the quadrupole 2,0 magnetic term reduced by 40%. The median formal precisions of 48 μas in right ascension and 70 μas in declination are comparable to recent S/X solutions for the more than 500 common sources. Noting that the X/Ka frame is derived from a limited geometry of only five observing sites, we discuss the importance of using full covariance information when evaluating this frame. Finally, we discuss the prospects for future improvements including the use of correlated noise to weight the solution.